An agent that modulates BRAF polypeptide activity can be an agent as described herein, such as a nucleic acid or a polypeptide, a naturally-occurring target molecule of a BRAF polypeptide (e.g., a BRAF substrate or receptor), a BRAF antibody, a BRAF agonist or antagonist, a peptidomimetic of a BRAF agonist or antagonist, or other small molecule.